The standard metal horseshoe which is popularly used today can cause several problems to a horse.
When an iron horseshoe is left on a horse for too long, the horseshoe prevents the hoof from expanding under the weight of the horse's weight as the hoof continues to grow downwardly. This causes contracted heels.
Hot forging of iron shoes by the farrier is a common practice to custom fit each iron shoe to the horse. This makes the shoeing process relatively expensive.
A pad is sometimes used in conjunction with an iron shoe. It is disposed between the iron shoe and the horse hoof. Its purpose is to help prevent bruising. However, when a pad is used, dirt, sand, small pebbles and other small hard particles can become lodged between the pad the horse hoof and work their way up inside the hoof wall to the coronet band over an extended period of use. This could cause lameness to the horse.